We wish to continue our studies on the attachment of the bacterial chromosome to the cell membranes. Specifically, we will attempt to answer the question whether some of the attachment sites previously discovered are regions of denaturation of the DNA. This will be done by studying the effect of single-strand specific endonucleases on the attachment and on the molecular weight of the DNA released by the enzyme. We will continue to study the role of the membrane in the replication of bacteriophage T4 DNA. We propose to determine whether the newly made DNA in a cancatemer of replicating phage DNA is proximal or distal to the membrane. This will be done by appropriate shearing and enzymatic degradation experiments followed by cell fractionation. We propose to initiate a study on the physical state of episomal DNA. We propose to determine whether episomal DNA (F factors, R factors) are present in cells in a compact state that can be isolated separately from the chromosome. If that is the case, this will be a source for protein ligands specific for episomes. We will also extend studies to the configuration of the bacterial chromosome.